RU2566896C1 - Steel cord for rubber reinforcement and conveyor tape - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: steel cord is created to reinforce rubber, during its manufacturing very high capacity can be achieved, and its weight can be favourably reduced, bend strength is increased; and conveyor tape is manufactured, in it the steel cord is used for rubber reinforcement. Steel cord 1 for rubber reinforcement with structure 1+6+(6+6), is made by twisting of individual steel wire threads 2, 3, 4a and 4b one time in same direction, and twisting coefficient is at least 9, but maximum 14, and outside diameter is maximum 4 mm.

EFFECT: higher strength.

4 cl, 4 dwg, 1 tbl

Description

Technical field

The present invention relates to a steel cord for reinforcing rubber and to a conveyor belt, and more particularly to a steel cord for reinforcing rubber, the manufacture of which can be achieved very high productivity, and the weight of which can be favorably reduced, and the bending strength is increased while maintaining tensile strength of the cord, and to the conveyor belt, which use a steel cord for reinforcing rubber.

State of the art

Steel cords formed from twisted steel wire threads are used as a reinforcing material for rubber products, for example, tires, conveyor belts and rubber hoses. One example is a twisted steel cord in which a plurality of strands forming a sheath are wound around an outer peripheral surface of a core strand (see, for example, Patent Document 1).

A steel cord 12 having a 7 × 7 structure similar to that shown in FIG. 4 are often used as a core in a conveyor belt. A steel cord 12 having a 7 × 7 structure is formed of six strands forming a sheath 14 wound around the outer periphery of one core strand 13. The core strand 13 is formed of six steel wire strands 13b wound around one steel wire strand 13a. The sheathing strands 14 are formed of six steel wire strands 14b wound around one steel wire thread 14a. Thus, three stranding processes are required to produce a steel cord 12 with a 7 × 7 structure, which leads to the problem of very low productivity in its manufacture if the cord has a small diameter. If a steel cord is used as a core in a conveyor belt, then a very high cord strength is required with its reduced weight and increased bending strength, in order to reduce the energy consumption required to drive the belt.

Patent document

Patent Document 1: Japanese Unexamined Patent Application No. 2012-36539 A

The tasks solved by the invention

The present invention is the creation of a steel cord for reinforcing rubber, the manufacture of which can be achieved very high productivity, and the weight of which can be favorably reduced, and the bending strength is increased, as well as the creation of a conveyor belt in which use a steel cord for reinforcing rubber.

Means for solving problems

To solve the problem indicated above, the steel cord for reinforcing rubber according to the present invention should be a steel cord for reinforcing rubber embedded in a rubber product, the cord having a 1 + 6 + (6 + 6) structure formed by twisting individual steel wire threads once in the same direction, while the torsion coefficient is at least 9, but not more than 14, and the outer diameter is not more than 4 mm.

The outer diameters of the individual steel wire strands are, for example, at least 0.35 mm, but not more than 0.75 mm. Of the two types of steel wire strands constituting the outer layer, the outer diameter of the steel wire strands of small diameter may be at least 60%, but not more than 90%, of the outer diameter of the steel wire strands of large diameter.

Also, the conveyor belt according to the present invention is a conveyor belt in which the steel cord for rubber reinforcement described above is embedded inside the belt in the form of a core.

Effect achieved using the invention

The steel cord for reinforcing rubber according to the present invention (hereinafter referred to as steel cord) has a 1 + 6 + (6 + 6) structure formed by twisting individual steel wire strands once in the same direction, thereby making it possible to complete cord production in one the process of twisting and increasing productivity in its manufacture. The cord has a torsion coefficient of at least 9, but not more than 14, and has an outer diameter of 4 mm or less, which is favorable for reducing weight and increasing bending strength, while ensuring the necessary strength of the cord.

In this way, the energy consumption necessary to drive a conveyor belt containing such a steel cord embedded inside the belt in the form of a core can be reduced.

Brief Description of the Drawings

FIG. 1 is a cross section of a steel cord according to the present invention;

FIG. 2 is a cross-sectional view of a conveyor belt containing a steel cord shown in FIG. 1, embedded inside the core ribbon;

FIG. 3 is a cross section of a steel cord with a 1 + 6 + (6 + 6) structure, in which steel wire strands are twisted in different directions in the inner layer and the outer layer; and

In FIG. 4 is a cross section of a steel cord with a 7 × 7 structure.

BEST MODE FOR CARRYING OUT THE INVENTION

The steel cord and conveyor belt according to the present invention are described below with reference to the embodiments presented in the drawings.

The steel cord 1 according to the present invention shown in FIG. 1 is a steel cord for rubber reinforcement used by embedding in a rubber product. Steel cord 1 has a structure of 1 + 6 + (6 + 6), and it is formed of: one steel wire thread 2, serving as a core; six steel wire threads 3, forming an inner layer located around the outer peripheral surface of the steel wire thread 2; and twelve steel wire strands 4a, 4b forming an outer layer located around the outer peripheral surfaces of the steel wire strands 3. The outer layer is formed of six larger diameter steel wire strands 4a and six small diameter steel wire strands 4b. The individual steel wire threads 2, 3, 4a and 4b are twisted once in the same direction, the adjacent steel wire threads being in contact with a maximum density. Both directions of torsion can be taken as torsion directions: S and Z.

The torsion coefficient K of the cord may be at least 9, but not more than 14, and the outer diameter D of the cord may be 4 mm or less. The torsion coefficient K is the length L of one torsion, referred to the outer diameter D of the cord (K = L / D). The outer diameter D of the cord exceeding 4 mm is unfavorable for reducing weight and increasing bending strength; thus, the diameter D should be 4 mm or less. To provide a practical level of cord strength, the outer diameter D of the cord should preferably be, for example, 2 mm or more. The torsion coefficient K, which is less than 9, leads to a noticeable decrease in the strength of the cord, and the torsion coefficient K, exceeding 14, leads to a noticeable decrease in bending strength; thus, the torsion coefficient K should be at least 9, but should not be more than 14.

The outer diameter of the individual, steel, wire threads 2, 3, 4a and 4b is, for example, at least 0.35 mm, but does not exceed 0.75 mm. Out of the discussion, for example, the issue of cost reduction, the steel wire thread 2 constituting the core wire thread and the large diameter steel wire threads 4a forming the outer layer should have the same outer diameter. The balance will be increased if, of the two types of steel wire strands 4a, 4b forming the outer layer, the outer diameter 4b of the steel wire of small diameter will be, for example, at least 60%, but not more than 90% of the outer diameter 4a of the steel wire threads of large diameter.

The steel cord 8 shown in FIG. 3 is formed of: one steel wire thread 9 serving as a core wire thread; six steel wire threads 10 forming an inner layer located around the outer peripheral surface of the steel wire thread 9; and twelve steel wire strands 11a, 11b forming an outer layer located around the outer peripheral surfaces of the steel wire strands 10. The outer layer is formed of six large diameter steel wire strands 11a and six small diameter steel wire strands 11b. The individual steel wire strands 10 are twisted in a certain direction around the outer peripheral surface of the steel wire thread 9 constituting the core wire thread. The individual steel wire strands 11a, 11b are twisted in a direction opposite to the direction in which the steel wire strands 10 are twisted, forming an inner layer around the outer peripheral surface of the steel wire thread 9.

The steel cord 8, therefore, has a 1 + 6 + (6 + 6) structure, the inner layer and the outer layer having different torsion directions, for which, therefore, two twisting processes are required to produce steel cord 8. Since the inner the layer and the outer layer have different torsion directions, the steel wire strands 10 of the inner layer and the steel wire strands 11a, 11b of the outer layer are not located with maximum density, but there is a certain free space between them.

More specifically, although the steel cord 1 according to the present invention shown in FIG. 1, has the structure 1 + 6 + (6 + 6), individual steel wire threads 2, 3, 4a and 4b are twisted once in the same direction, which ensures the possibility of a minimum number of twisting processes (i.e., one process twisting) and increase productivity in its manufacture. Since the inner layer and the outer layer are twisted in the same direction, the steel wire threads 3 and the steel wire threads 4a, 4b are almost in surface contact (increased contact area), which is favorable for increasing the bending strength.

The steel cord 1 according to the present invention can be used by embedding it as a reinforcing material in various types of rubber products, for example, tires, rubber hoses, marine hoses and safety devices located between the side of the boat and the ship. As shown in FIG. 2, steel cord 1 is particularly preferably used as the core 7 of the conveyor belt 5.

A large number of steel cords 1 are arranged in the conveyor belt 5 at predetermined intervals along the width of the belt and in the direction of its length, and are closed between the upper rubber coating 6a and the lower rubber coating 6b.

The core cords 7, bearing a tension load when pulling the conveyor belt 5, must have very high bending strength; thus, the steel cord 1 according to the present invention is very suitable for use as such. The use of steel cords 1 of reduced diameter provides the possibility of reducing the thickness of the conveyor belt 5, thereby contributing to the reduction of the weight of the conveyor belt 5. This also provides the opportunity to reduce the energy consumption required to drive the belt.

EXAMPLES

As shown in Table 1, steel cords having the structure shown in FIG. 1 having different torsion ratios K and outer diameters D (see Working Examples 1-3 and Comparative Examples 1-3); steel cord having the structure shown in FIG. 3 (see Comparative Example 4), and a steel cord having the 7 × 7 structure shown in FIG. 4 (see Typical Example) was embedded in unvulcanized rubber (NR / SBR) (natural rubber / elastomeric copolymer of butadiene and styrene) and vulcanized under the same conditions (148 ° C for 25 min) to produce test specimens with the following properties: determined (see Table 1). The test results are presented in Table 1.

The outer diameters of the steel wire strands in Working Examples 1-3 and Comparative Examples 1-4 were as follows:

Steel wire threads marked with pos. 2, 4a in FIG. 1 and pos. 9, 11 in FIG. 3, had a diameter of 0.59 mm

Steel wire threads marked with pos. 3 in FIG. 1 and pos. 10 in FIG. 3, had a diameter of 0.55 mm

Steel wire threads marked with pos. 4b in FIG. 1 and pos. 11b in FIG. 3, had a diameter of 0.45 mm

The outer diameters of the steel wire strands in the Common Example were as follows:

Steel wire thread indicated by pos. 13a in FIG. 4, had a diameter of 0.41 mm

Steel wire thread indicated by pos. 13b, 14a in FIG. 4, had a diameter of 0.35 mm

Steel wire thread indicated by pos. 14b in FIG. 4, had a diameter of 0.31 mm

Cord Production

The amount of time required for the manufacture of individual steel cords was determined and compared with the Common example, the index of which was taken as 100. The smaller the value obtained, the greater the productivity.

Cord strength

Individual steel cords were stretched in the direction of length to break and the load at break was taken as the strength of the cord.

Tape weight

The weight of individual test samples was determined and compared with the Common example, the index of which was taken as 100. The larger the value, the greater the weight.

Flexural strength

Separate test specimens were wrapped around a pulley with a diameter of 90 mm and repeatedly bent, and the number of bends was determined until the cord broke. This amount was compared with a similar parameter achieved in the Normal example, the index of which was taken as 100; however, a large value indicated a very high bending strength.

Rubber adhesion

Separate test specimens were kept under the initial conditions regarding bonding, humidity and temperature (50 ° C, relative humidity 95%, duration 5 weeks), after which the fraction of residual bonding of rubber with the surfaces of the cords was determined. The larger the value obtained, the higher the adhesion strength between cord and rubber.

Table 1 Common example Working examples Comparative examples one 2 3 one 2 3 four Cord structure 7 × 7 1 + 6 + (6 + 6) Number of torsions 3 one 2 Torsion direction S / z Z / z S / z K - torsion coefficient of the cord 7.5 9.6 11,4 13.3 7.9 14.8 11,4 11,4 D - outer diameter of the cord (mm) 2.9 2.6 4.4 2,8 Cord Production one hundred fifty 80 Cord Strength (kN) 9.3 9.3 9.5 9.7 8.2 9.8 27.0 9.3 Tape Weight (Index) one hundred 98 99 Flexural Strength (Index) one hundred 105 102 one hundred 108 82 26 101

The initial adhesion of rubber to the cord (%) 95 Adhesion of rubber to the cord (%) after exposure to the test conditions (at certain temperature and humidity) thirty one hundred

From Table 1 it is obvious that Working examples 1-3 were more favorable than the Common example and Comparative example 4 in terms of performance in the manufacture of cord and weight reduction tape. It is also obvious that Working Examples 1-3 are suitable for providing flexural strength and tensile strength of the cord comparable or higher than those obtained in the General Example.

The list of reference positions in the drawings

1 - Steel cord according to the present invention

2 - Steel wire thread, representing the core wire thread

3 - Steel wire thread representing the inner layer

4a, 4b - Steel wire thread representing the outer layer

5 - conveyor belt

6a - Top rubber coating

6b - Lower rubber coating

7 - Core

8 - Another steel cord with a structure of 1 + 6 + (6 + 6)

9 - Steel wire thread, representing the core wire thread

10 - Steel wire thread representing the inner layer

11a, 11b - Steel wire thread representing the outer layer

12 - Steel cord with a 7 × 7 structure

13 - Core strand

13a, 13b - Wire

14 - Shell forming strand

14a, 14b - Wire.

Claims (4)

1. Steel cord for reinforcing rubber, used by embedding it in a rubber product having a 1 + 6 + (6 + 6) structure formed by twisting individual steel wire threads once in the same direction, the torsion coefficient of which is at least 9, but not more than 14, and the outer diameter is not more than 4 mm 2. A steel cord for rubber reinforcement according to claim 1, wherein the individual steel wire strands have outer diameters of at least 0.35 mm but not more than 0.75 mm. 3. Steel cord for rubber reinforcement according to claim 1 or 2, in which of the two types of steel wire thread constituting the outer layer, the steel wire thread of small diameter has outer diameters of at least 60%, but not more than 90% , the outer diameters of steel wire strands of large diameter. 4. Conveyor belt, in which, as the core, a steel cord is embedded for rubber reinforcement according to any one of paragraphs. 1-3.

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